Rotary actuator and indicator

ABSTRACT

An indicator having an armature with spaced magnetic poles mounted to pivot back and forth on its axis to match indicia on the armature with fixed indicia at each end position of the pivotal motion. The armature poles are attracted alternately to the two end positions by stator poles energized by a coil supplied with current that corresponds in magnitude or direction of flow with the operating condition under surveillance. Pivotal motion of the armature is limited by a pin, either on the armature or on the stator, that fits into an annular slot in the stator or armature. The armature can move axially to a limited extent, and to hold the disc in either of its limit positions, the ends of the slot are further axially indented to receive the pin. The armature is free to move axially far enough to disengage the pin from the indentations but not completely free of the slot.

United States Patent Loughran, Jr. [451 June '20, 1972 ROTARY ACTUATORAND INDICATOR Primary Evaminer-Harold Broome [72] inventor: Eugene F.Loughran, Jr., Oakville, Conn. Attorney-Donald Gmene [73] Assignee:North American Philips Corporation, [5 7] ABSTRACT Waterbury, Conn. Anindicator having an armature with spaced magnetic poles Filed; g- 1969mounted to pivot back and forth on its axis to match indicia on [21]APPL No 852,634 the armature with fixed indicia at each end position ofthe pivotal motion. The armature poles are attracted alternately to thetwo end positions by stator poles energized by a coil U-S- t t uppliedcurrent that corresponds in magnitude or 50/18 direction of flow withthe operating condition under surveil- [531 Field "335/272, 138; 340/373lance. Pivotal motion ofthe armature is limited by a pin, either on thearmature or on the stator, that fits into an annular slot [56]References (med in the stator or armature. The armature can move axiallyto a UNITED STATES PATENTS limited extent, and to hold the disc ineither of its limit positlons, the ends of the slot are further axiallylndented to 2,644,939 receive the pin The armature is free to moveaxially far 3 4/1968 ouellene-u enough to disengage the pin from theindentations but not l Ouellelte 'eoe335/272 completely free ofthe lot3,440,582 4/1969 Gerspach ..335/l38 15 Claims, 10 Drawing FiguresPATENTEnJum 1912 3,671,900

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nzvoe cvs ROTARY ACTUATOR AND INDICATOR This invention relates to anactuator and an indicator operating in a rotary, or pivotal, motionbetween fixed limits. In particular it relates to an actuator that hasan armature that moves axially between a quiescent position and anenergized position, with means to rotate the armature from one angularlimit to the other.

In the field of built-in test equipment there is a continual effort toreduce the size, complexity, and power requirements of indicators thathave two indicating positions to show that the equipment under. test isin one or the other of two conditions, for example, either operative orinoperative. Moreover, the indicators must be as free as possible fromgiving spurious, ambiguous, or incorrect responses. This means, amongother things that the indicator must not jump out of position due tomechanical shock, to which such indicators are frequently subjected inthe environment in which they are operated.

In accordance with these requirements, the present invention comprisesan indicator having a rotary actuator operated electromagnetically. Theactuator comprises a coil, stator pole members magnetically energizedwhen the coil carries current, and an armature to which indicia may beattached. The armature has permanent magnetic poles that align with thestator in one of two ways, depending on the direction of current flow inthe coil. When the armature and its attached indicia are in one angularposition, an alignment between the indicia and a fixed identificationstructure establishes that the armature is in that particular positionwhich corresponds to one condition of the equipment under test. Reversalof the armature to the other position results in visual indication ofmovement of the armature and therefore of the fact that the equipmentunder test has shifted to the other condition.

In order to limit the movement of the armature to just two positions andto hold it in either of those positions when the coil is not energized,either the armature or the stationary part of the device has two mainabutments that engage stop means on the other part of the device. Twoadditional abutments cooperate with stop means to hold the armature ineither end position after the coil has been transferred to thatposition. Magnetic attraction between the permanently magnetized polesof the annature and the stator poles holds the armature FIG. 7 is across-sectional view of a different embodiment of the invention;

FIG. 8 is a cross-sectional view of another embodiment of the invention;

FIG. 9 is a cross-sectional view of the latching'plate in FIG. 8; and

FIG. 10 is a plan view of the indicator showing certain angularrelationships.

The indicator 11 in FIG. 1 comprises an outer shell 12 having agenerally opaque face 13 with three wedge-shaped windows 14 equallyspaced around the center of the face 13. Part of the face has beenbroken away to show some of the internal features of the indicatorincluding a spacer 16 on which the is supported and the disk 17immediately behind the face. The disk has three wedge-shaped flags I8spaced to correspond to the electromagnetic driving unit comprising acentral ferromagnetically sofi steel core 19 on which a stator coil 21is mounted. At one end of the core 19 is a sofl steel disk 22 havingseveral integral strips 23 extending up alongside the coil 21 andtemiinating in pole portions 23a. Near the other end of the core 19 isanother ferromagnetically soft steel disk 24 having another set ofstator poles 24a extending from its edge in the same direction as thepole portions 23a. The spacer 16 axially in position so that the stopmeans engages the appropriate abutments until a net current in thereverse direction so magnetizes the stator poles that the armaturepolesare repelled. The armature first moves to disengage the abutmentsfrom the stop means, after which the armature is free to rotate to thealternative position under the combined magnetic forces of the statorand rotor poles. Once the armature reaches the alternative position, theabutments and stop means will again engage and force the armature toremain in place due to the attraction between the stator poles and thearmature poles. Even after the current through the coil has been cutoff, the armature will remain in that position due to the magneticattraction of the permanently magnetized armature poles for that set ofstator poles. The armature cannot easily be shaken out of positionbecause it would require a combined axial and rotary motion to dislodgeit.

The invention will be further described in the following specificationtogether with the drawings in which:

FIG. I is a front elevational view of an indicator constructed accordingto the invention with parts broken away to show the interiorconstruction thereof;

FIG. 2 is a cross-sectional side view of the indicator of FIG. 1;

FIG. 3 is a perspective view of the stator structure of the indicator ofFIG. 2;

FIG. 4 is a perspective view of the movable member of the indicator inFIG. 1;

FIG. 5 shows the angular relationship between the stop on the statorstructure and the abutments on the movable member of the indicator;

FIG. 6 is a side view of the movable member and the stop on the statorstructure of FIG. 5.

rests on top of all of the stator poles 23a and 24a.

The movable part of the indicator includes a support member 26 having acentral bearing 27 supported on an extension 19a of the core 19. Theouter perimeter of the support 26 has a downwardly turned rim 28 and thedisk 17 is directly afiixed to the upper surface of the support member26. A permanently magnetized ring 29, which may be an elastomericmaterial, is attached to the outer surface of the rim 28 to provide thenecessary magnetic field or fields to interact with the stator poles 23aand 24a to move the support member 26. The core 19 also helps to spacethe various members of the electromagnetic driving unit properly withinthe shell 12. The lower end of the core has a portion 19b of reduceddiameter to fit snugly into a central hole 22a in the disk 22. Near theupper end of the core 19 is another portion of reduced diameter whichfits snugly into a matching hole 24b in a disk 24, and the uppermost endof the extension 19a abuts against the inner surface of the face 13. Acap 30 closes and seals the lower end of the shell 12 to keep out dirtand contaminating vapors.

One of the reasons for providing specific spacing within the shell 12 isto permit a limited amount of axial movement of the movable member,including the support member 26, to allow the disk 17 to shift to theposition indicated in dot-and-dash lines and identified by referencenumeral 17a. The purpose of providing for this limited axial movement ofthe movable member will be explained in connection with FIGS. 3-6. 1

FIG. 3 shows a perspective view of the electromagnetic driving unit andin this figure it may be clearly seen that there are three equallyspaced stator poles 23a and three equally spaced stator poles 24a spacedmidway between the poles 23a. Near the outer part of the disk 24 is avertical stop pin 31 which limits the angular movement of the supportmember 26 by engaging abutment edges therein.

The movable member is shown in FIG. 4 and it includes two notches 32 and33 in the rim 28. Between the two notches is a section 34 of reducedheight, which is to say that the abutment edges 36 and 37 of the notches32 and 33, respectively, are axially somewhat longer than the abutmentedges 38 and 39 of those same notches.

Surrounding the rim and firmly bonded thereto is the permanentlymagnetized rotor ring 29 which has, in this embodiment, six poles, threeof which are north poles and three of which are south poles. The polesare arranged alternately north and south around the ring 29 and the ringis magnetized so that one of the north poles has its center line on oneof the abutment edges, in this case the abutment 36. This produces thedesired holding effect to keep the rotor assembly in place.

The ring 29 may be made of a rubberlike material containing I ferrite'toallow it to be permanently magnetized.

FIG. 5 shows the angular spacing between the notches 32 and 33 relativeto the angular spacing between permanently magnetized pole areas of thering 29. In the embodiment shown there are six permanently magnetizedpole areas, three of which are north pole areas and the other three ofwhich are south pole areas, all equally spaced around the ring 29. Theangular dimensions of the notches 32 and 33 and their spacing of about53 between their centers is such that, taking into account the diameterof the stop pin 31, the support member 26 is able to move onlyapproximately 55 which is slightly less than the spacing betweenadjacent poles 22a and 24a in the ring 29. Since the normal magneticattraction of the permanently magnetized poles in the ring 29 withrespect to the stator poles 23a and 24a is such that the ring attemptsto pull the support member 26 farther than is permissible, thelimitation of movement of the support member to only 55 means that wheneither of the notches 32 and 33 engages the stop pin 31, there is aresidual magnetic force that holds the support member 26 so that eitherthe abutment edge 36 of the abutment edge 37 presses against the pin 31.The angular width of notches 32 and 33 is slightly greater than theangle necessary to allow the pin 31 to fit into the notches. As a resultthere is a slight space between the abutment edges 38 and 39 and the pin31 when the notches 32 and 33, respectively, fit over the end of thepin.

While the spacing between the three poles 23a is 180 and the spacingbetween the three poles 24a is 180, the poles 230' are slightlydisplaced with respect to the poles 24a so that the spacing of adjacentpoles are alternately 57 and 63. This has been found to increase theaxial thrust about to percent over what the thrust would be with equalaxial spacing between each pole 23a and the poles 24a on each side ofit.

The interfitting of the pin 31 into the notches 32 and 33 is shown inFIG. 6 where the pin is within the notch 32. FIG. 6 also shows the axialspacing between the bottom edge of the rim 28 and the edge 34. Ineffect, the entire space between the abutment edges 36 and 37 may beconsidered to be a relatively side slot with two deeper but narrowernotches 32 and 33 at the ends.

The operation of the electromagnetic driving unit is such that thepermanent magnetic fields of the poles in the ring 29 cause the ring 29and therefore the support member 26 to be attracted axially toward theends of the stator poles 23a and 24a when no current is applied to thecoil 21. When current is applied to the coil-21 to magnetize the statorpoles 23a and 24a with the proper magnetic polarities to rotate themovable member, this same magnetic field relationship repels the polesin the ring 29 axially toward the face 13 so as to place the disk 17 inthe position 17a in FIG. 2. This movement is sufficient to permit theend of the pin 31 to clear the edge 34, as may best be seen by referenceto FIG. 6, but not beyond the edges 36 and 37, that is, not beyond thebottom edge of the rim 28. Simultaneously, the effect of the magneticfields of the stator poles 23a and 24a is such as to rotate the ring 29and hence the support member 26 to the alternative position. Withreference to FIG. 6, this would be the position in which the notch 33would be over the pin 31. As long as the coil 21 remains energized withthat polarity, the support member 26 will be in position to have thenotch 32 engage the pin 31. Moreover, even after energizing current hasbeen removed from the coil 21, the axial magnetic attraction between thepermanent poles in the ring 29 and the stator poles 23a and 24a will besuch as to maintain the support member 26 in the same angular positionbut axially retracted as shown in solid lines in FIG. 2. In thisposition the stop pin 31 engages sufficiently deeply into the notch 33so that the abutment edge 39 would prevent the support member 26 fromturning even if the indicator 11 were subjected to a rotary shakingaction of sufiicient force to overcome the magnetic force of attractionbetween the poles in the ring 29 and the stator poles 23a and 240.Before the movable member could be moved to its alternative position,there would have to be, in addition to the rotary shaking motion, anaxial shaking motion occurring at the same time. This is the type ofmotion that would be necessary to allow the barrier formed by theabutment edges 38 and 39 and the edge 34 to jump over the stop pin 31.

The embodiment in FIG. 7 includes many of the same parts as theembodiment in the earlier figures and it is therefore unnecessary todescribe these parts in detail. However, while the movable part of theindicator in FIG. 2 is shown supported on a fixed extension 19a, themovable member, or armature, 41 in FIG. 7 is affixed to a rotatableshaft 42 which in turn is supported in bearings 43 and 44 spaced apartalong a hollow core 46 that extends through the coil 21. The shaft 42 isfree not only to rotate in the bearings 43 and 44 but also to slidelongitudinally. A retaining washer 47 is attached to the other end ofthe shaft to limit the extent of longitudinal movement and a thrustwasher 48 is placed on the shaft between the armature 41 and the bearing44.

The stator poles 23a and 24a are arranged in the same configuration asin FIG. 3 and the same stop, or index, pin 31 is provided to limit therotation of the armature 41 by engaging in a notched latching section ofthe downwardly turned rim 28 of the armature 41. The latching sectionhas the same notches 32 and 33 and the same abutment edges as thearmature shown in FIG. 6.

The operation of the embodiment in FIG. 7 is nearly the same as theoperation of the embodiment in FIG. 2, except that the whole shaft 42moves longitudinally and rotates instead of just the armature 41.Indicia on the surface of the armature 41 are visible through windows intheface 13 to indicate whether the armature 41 is in one of the other ofits end positions.

The embodiment in FIGS. 8 and 9 differs in that it has an armature 29 atone end and an indicator disk 51 at the other end of an elongated rotorshaft 52. This shaft is supported by the same bearings 43 and 44 as theshaft 42 in FIG. 7 but it is unnecessary to provide a retaining washersince the indicator disk 51 serves that purpose.

Instead of providing a fixed stop pin, as in the earlier embodiment, theembodimentin FIG. 8 has a stop pin 53 affixed to the armature 52 andengaging an-index plate 54. The relationship between the armature 49 andthe stop pin 53 and the plate 54 is better shown in FIG. 9 where it maybe seen that the index plate has two portions 56 and 57 pressed out ofplane of the remainder of the plate 54 and toward the armature 49. Aslot is formed between these portions 56 and 57 and the edges of theseportions form abutment edges 58 and 59 which limit the maximum arcuatemovement of the armature 49. Between the portions 56 and 57 is anotherportion of the plate 54 indicated by reference numeral 61. This portiondoes not extend upwardly as far as the portions 56 and 57 but its sideedges 62 and 63 do form abutment edges that capture the pin 53 in eitherof its positions in a manner similar to the capture of the pin 31 inFIG. 6. The space 64 between the abutment edges 58 and 62 corresponds tothe notch 32 in FIG. 6 and the space 66 between the abutment edges 59and 63 corresponds to the notch 33 in FIG. 6.

The operation of the structure in FIGS. 8 and 9 is, insofar as thelatching is concerned, the converse of the operation of the otherembodiment. In this instance the stop pin is on the rotor and thenotches and abutment edges are on the stationary part of the device,whereas in the previous embodiment it was just the reverse. However, thearmature 49 does follow the same longitudinal and rotary motion as themovable member 26 in the embodiment in FIGS. 1-6.

The embodiment in FIGS. 8 and 9 has an additional advantage due to thefact that in the quiescent position with the stop pin in either of thenotches and 66, the rotor 49 is drawn longitudinally toward the coil 21which causes the indicator disk 51 to move close to the face 13 throughwhich indicia on the indicator disk 51 are to be observed. On the otherhand, in the quiescent condition of the embodiment of FIG. 2,

for example, the indicator disk 17 is as far away from the face 13 asthe available space permits. As a result there is less parallax in theembodiment in FIG. 8 than in the embodiment in FIG. 2 during theimportant intervals of time when the disk 51 is in one of its twoindicating positions. The reduction in parallax means that the indiciaon the disk 51 match more closely the indicia of the face 13.

FIG. shows the angular relationship between the poles 23a and 24a, thestop pin 31, and the indicia 18. As may be noted, the poles 24a aredisplaced counter-clockwise 3 with respect to the poles 23a. Also shownin this figure is an end plate 52 with notches 53 to position the poles23a. The three indicia sectors each have an included angle of 60, andthe counter-clockwise edge of each is on the center line of one of thepoles 24a when the indicator disk 17 is in the counterclockwise positionshown.

What is claimed is:

l. A rotary actuator comprising: a coil, an armature to be rotated overa range of positions between first and second end positions; a shaftpivotally supporting said armature; first and second stator polesmembers magnetically coupled to said coil to be mutually oppositelymagnetically energized thereby and having angularly spaced stator poles;stop means fixed with respect to said pole members; first and secondabutments on said armature to engage said stop means to limit angularmovement of said armature to said range of positions; third and fourthabutments to engage said stop means to maintain said armature in eitherof said end positions when said coil is not energized; and a permanentlymagnetized section on said armature magnetically coupled to said statorpoles, said armature being axially movable to disengage said third andfourth abutments from said stop means when coil is energized tomagnetize said stator poles to shift said armature from one of said endpositions to the other.

2. The actuator of claim 1 in which said armature comprises a disk andsaid abutments comprise slotted edge portions thereof.

3. The actuator of claim 2 in which said disk has an axial flange andsaid slotted edge portions are axial slots in said flange.

4. The actuator of claim 2 in which said slotted edge portions comprisea main angular slot, the ends of which form said first and secondabutments, and said stop means comprises an axially extending memberwithin said slot and having an axial length greater than the maximumaxial movement of said armature.

5. The actuator of claim 2 in which said edge portions comprise an axialflange having an angular slot therein defined between first and secondaxially extending walls forming said first and second abutments, saidslot being axially deeper at each end than in the middle thereof anddefined by an edge having third and fourth walls facing said first andsecond walls, respectively but shorter axially, than said first andsecond walls and forming said third and fourth abutments, said stopmeans comprising an axial projection having a small enough angular widthto fit between said first and third abutments or between said second andfourth abutments.

6. The actuator of claim 1 in which said shaft is a ferromagneticallysoft cylinder extending through said coil and comprising a coretherefor.

7. The actuator of claim 6 in which said shaft extends through said coiland said first and second stator pole members are affixed to oppositeends of said shaft.

8. The actuator of claim 7 in which said stop means comprises an axialpin affixed to one of said stator pole members.

9. The actuator of claim 7 in which said first stator pole member has aplurality of evenly spaced stator poles extending therefrom axiallyalong the outer surface of said coil and said second stator pole memberhas a corresponding plurality of evenly spaced stator poles interleavedwith the ends of the stator poles from said first stator pole member.

10. The actuator of claim 9 in which said first and second end positionsof said armature are angularly spaced apart by a smaller angle then theangle between the center of a pole from said first stator pole memberand the center of the adjacent pole from said second stator pole member.t

11. The actuator of claim 1 comprising, in addition: an indicatorattached to said armature to move therewith and having angularly spacedindicia thereon; and a cover over said indicator and having window meansthrough which said indicia may be seen when said armature is in saidfirst end position but not when said armature is in said second endposition.

12. A rotary actuator comprising: a coil, stator pole means magneticallycoupled to said coil; an armature rotatable between first and secondangular positions and comprising permanently magnetized poles, saidarmature also being free to move axially a predetermined distance fromone axial position when said coil is energized to an opposite axialposition when said coil is not energized; latching means to hold saidarmature in either of said positions, said latching means comprising astop, first and second abutments to engage said stop to fix the maximumangular movement of said armature, and third and fourth abutmentsbetween said first and second abutments and spaced therefrom wherebysaid stop may fit between said first and third abutments in one of saidpositions and between said second and fourth abutments in the other ofsaid positions, said third and fourth abutments having a smaller axialdimension than the extent of movement of said armature whereby saidarmature can move past said third and fourth abutments when said coil isenergized to magnetize said stator poles to shift said armature from oneof said angular positions to the other.

13. The actuator of claim 12 in which said stop is affixed to saidstator pole means.

14. The actuator of claim 12 in which said stop is affixed to saidarmature.

15. The actuator of claim 12 in which said stop extends axially fromsaid armature and said actuator comprises, in addition, a substantiallyplanar index plate having portions raised above the plane of said plateand having edges comprising said first and second abutments, said platehaving an additional portion between said raised portions, saidadditional portion having edges defining said third and fourthabutments.

1. A rotary actuator comprising: a coil, an armature to be rotated overa range of positions between first and second end positions; a shaftpivotally supporting said armature; first and second stator polesmembers magnetically coupled to said coil to be mutually oppositelymagnetically energized thereby and having angularly spaced stator poles;stop means fixed with respect to said pole members; first and secondabutments on said armature to engage said stop means to limit angularmovement of said armature to said range of positions; third and fourthabutments to engage said stop means to maintain said armature in eitherof said end Positions when said coil is not energized; and a permanentlymagnetized section on said armature magnetically coupled to said statorpoles, said armature being axially movable to disengage said third andfourth abutments from said stop means when coil is energized tomagnetize said stator poles to shift said armature from one of said endpositions to the other.
 2. The actuator of claim 1 in which saidarmature comprises a disk and said abutments comprise slotted edgeportions thereof.
 3. The actuator of claim 2 in which said disk has anaxial flange and said slotted edge portions are axial slots in saidflange.
 4. The actuator of claim 2 in which said slotted edge portionscomprise a main angular slot, the ends of which form said first andsecond abutments, and said stop means comprises an axially extendingmember within said slot and having an axial length greater than themaximum axial movement of said armature.
 5. The actuator of claim 2 inwhich said edge portions comprise an axial flange having an angular slottherein defined between first and second axially extending walls formingsaid first and second abutments, said slot being axially deeper at eachend than in the middle thereof and defined by an edge having third andfourth walls facing said first and second walls, respectively butshorter axially, than said first and second walls and forming said thirdand fourth abutments, said stop means comprising an axial projectionhaving a small enough angular width to fit between said first and thirdabutments or between said second and fourth abutments.
 6. The actuatorof claim 1 in which said shaft is a ferromagnetically soft cylinderextending through said coil and comprising a core therefor.
 7. Theactuator of claim 6 in which said shaft extends through said coil andsaid first and second stator pole members are affixed to opposite endsof said shaft.
 8. The actuator of claim 7 in which said stop meanscomprises an axial pin affixed to one of said stator pole members. 9.The actuator of claim 7 in which said first stator pole member has aplurality of evenly spaced stator poles extending therefrom axiallyalong the outer surface of said coil and said second stator pole memberhas a corresponding plurality of evenly spaced stator poles interleavedwith the ends of the stator poles from said first stator pole member.10. The actuator of claim 9 in which said first and second end positionsof said armature are angularly spaced apart by a smaller angle then theangle between the center of a pole from said first stator pole memberand the center of the adjacent pole from said second stator pole member.11. The actuator of claim 1 comprising, in addition: an indicatorattached to said armature to move therewith and having angularly spacedindicia thereon; and a cover over said indicator and having window meansthrough which said indicia may be seen when said armature is in saidfirst end position but not when said armature is in said second endposition.
 12. A rotary actuator comprising: a coil, stator pole meansmagnetically coupled to said coil; an armature rotatable between firstand second angular positions and comprising permanently magnetizedpoles, said armature also being free to move axially a predetermineddistance from one axial position when said coil is energized to anopposite axial position when said coil is not energized; latching meansto hold said armature in either of said positions, said latching meanscomprising a stop, first and second abutments to engage said stop to fixthe maximum angular movement of said armature, and third and fourthabutments between said first and second abutments and spaced therefromwhereby said stop may fit between said first and third abutments in oneof said positions and between said second and fourth abutments in theother of said positions, said third and fourth abutments having asmaller axial dimension than the extent of movement of said armaturewhereby said armature can move past said third anD fourth abutments whensaid coil is energized to magnetize said stator poles to shift saidarmature from one of said angular positions to the other.
 13. Theactuator of claim 12 in which said stop is affixed to said stator polemeans.
 14. The actuator of claim 12 in which said stop is affixed tosaid armature.
 15. The actuator of claim 12 in which said stop extendsaxially from said armature and said actuator comprises, in addition, asubstantially planar index plate having portions raised above the planeof said plate and having edges comprising said first and secondabutments, said plate having an additional portion between said raisedportions, said additional portion having edges defining said third andfourth abutments.